When I tell people I am interviewing Noel Fielding, reactions range from "Who?" to "He's a genius." He has been a comic idol in my household right from the start when the BBC's series, The Mighty Boosh, seemed a minority taste: obscure, outlandish, an in-joke. Since those days, the Boosh has got mightier by the minute and become a mainstream phenomenon (with radio shows, three television series, live shows at the O2 and Wembley) while never losing its cult feel. I am longing to meet Fielding – partly to show off to his fanbase at home. Noel Fielding is known to Boosh-watchers as sweet, narcissistic, punky Vince Noir, best friends with Julian Barratt's defensive jazz bore, Howard Moon. Their humour is zany, beguiling and incongruous: the cast includes a chatty moon, a talking ape and a tiny shaman called Naboo played by Fielding's brother.

But this year Barratt and Fielding are reinventing themselves. Barratt is getting his teeth into theatre while Fielding's career becomes ever more fantastical: he not only has a new art book out, The Scribblings of a Madcap Shambleton, but also – although The Mighty Boosh seems an impossible act to follow – is about to launch, in January, his first solo series on E4. There have been rumours about its name ("Boopus" was one working title). But now it is official: Noel Fielding's Luxury Comedy.

It is just before noon at Waterstone's, in Manchester. It is a weirdly hot November morning and the fans are out in force. They sit on the pavement, pressed up against the storefront glass. Inside, more fans are jammed behind a metal barrier. It is as if we were all at a zoo, waiting to see a rare animal. In the first series of The Mighty Boosh, Fielding and Barratt were zookeepers – it is our turn now. Some girls have black rings under their eyes: they have been here since 4am. But the atmosphere is happy and warm. Fielding is about to paint the shop window – it will take him an hour (he will be doing something similar in London's Golden Square, on Saturday). I am at the front, an amazing chance not only to see him perform but to study him as if in an anthropological experiment: Noel Fielding in close-up.

And now there is a ripple through the crowd. A flash of brilliant-yellow PVC boiler suit, silver high-heeled boots, hair black as squid's ink – and he's here. His designer, Dave Brown (who plays Bollo, the ape in The Mighty Boosh) is alongside him. Fielding grabs the microphone. "Hello Manchester," he says, and starts to confide about the night he has just spent at Malmaison, a boutique hotel, exclaiming at how dark it was and how he thought he might run into a vampire: "I slept in a little coffin". What I notice is his talent for talking to hundreds of people as if to his best friend. At other times, he seems dreamily to be talking to himself. Then he steps outside and the fans hold out their arms. He is greeted like a long-lost brother. It is all hugs and sweets (which he gratefully accepts and starts to chew).

The charm is about more than seeing Noel Fielding. It is about Noel Fielding seeing for us. Because what happens, with Fielding, is that nothing is allowed to stay pedestrian. For a moment, you are in an ordinary shop, then it gets the Fielding treatment – Waterstone's becomes a ridiculous enigma. He marvels at the ladder with which he has been supplied: "That is the smallest ladder I've ever seen." Then his eye catches a Christmas tree, draped in a sheet, to protect it from paint. He sees this as wacky beyond belief. He gives it a personality ("embarrassed"). It is "the ghost of a Christmas tree". It is "wearing a dressing-gown". This is the way he sees the world. He claims he has no idea what he and Brown are to paint: "We can think of something I am sure, we both have a degree."

His yellow boiler suit has the slogan "I love art" with hearts painted in black and scarlet. He has got a socking great crucifix round his neck. He kicks off one of his silver boots and hobbles about. Someone asks why he has only taken one boot off. His answer leaves none of us any the wiser: "I have a phobia about my feet, they are like raven's talons, some of the worst feet you have ever seen." The heat is intense and he is sweltering in his boiler suit. "It is killing me," he exclaims to which comes the predictable roar: "Take it off!" but he is not about to do a rock star stunt and throw his boiler suit into the crowd. "If I took it off, it would be ridiculous. If I paint in my pants, we will get into the paper for the wrong reasons."

It is interesting to see what a natural he is at stand-up (which is how he started and met Julian Barratt – at a comedy gig in north London in 1998). And while the repartee goes on he is actually producing a painting: "I am trying to make a W out of cats," he says, twirling his brush. "That's what's going on here." Three blue cats with jaunty paws and brutish teeth are born and, as a finishing touch, have scarlet paint thrown at them. The effect is like aboriginal painting run amok. "This would look better from the moon," he observes. Throughout, cameras and mobile phones are flashing. He remarks: "I remember the days when we used to live our lives, instead of watching ourselves on screens." He reminds himself, and us, to be, but it is a sweet aside, not a lecture. His eye catches the ladder again: "I am going to be auctioning this small ladder off for charity."

In the hour between painting and signing, I am escorted upstairs to an office where Fielding and Brown are tucking into Costa sandwiches from over the road. I shake hands with Fielding and notice his palms are covered with acrylic paint – like living palettes. He looks knackered – his complexion grey in spite of his expressive features and all that laughter (he used to be known for his ability to work after staying up all night). He has shed the yellow boiler suit at last, swapping it for a purple tie-dyed T-shirt. The crucifix (from The Great Frog, his favourite London jeweller) is still on board. Fielding is keen for me to understand that he and Brown have known each other half a lifetime. They reminisce about Croydon College where they first met. It was Fielding's ambition, in those days, to become a fine artist. Brown remembers: "He had this big box, the sort you keep fishing tackle in – that you only have if you are a serious artist." Fielding enthuses: "I used to put green slime, made of Plasticine, over it so no one would touch it and people would go, 'Ugh … what is that, diseases?' "

Their tutor was the Turner-prize nominated Dexter Dalwood, who writes the introduction to Fielding's book. This is what he says: "Sometime in the late 80s, I walked into Croydon College to teach a BTec graphic design class … 'fine art'. I saw across the room a boy who resembled an Easter Island head, cheeky and kind of keen. I tried to guide him through life drawing (inept), print-making (hopeless), painting (er, what?)." Some of his painting was so bad, says Dalwood, it "flipped into genius".

It seems your art teacher thought your work was useless? "Yeah, that is Dexter's sense of humour," says Fielding. "He was quite cutting." And were your school reports equally bad? Fielding says he was good at art and English and a natural at biology – "I didn't even study and got an A." He was "rubbish" at everything else – especially maths and spelling.

He seems genuinely hurt by his teacher's "humour" in dismissing his work – though it is not always obvious when he is being serious. The book is great: fun and funny. But what he is doing is high-risk – mixing comedy with fine art. Fielding writes: "I couldn't make a choice between the two. It was always my ambition to make comedy with an art-school slant, and art that could be funny instead of po-faced." So is he in a grand tradition – who does he see as the comedians of art history? "Jean Dubuffet – his stuff is ridiculous. Jean-Michel Basquiat. Warhol is a comedian. And Dalí. And Magritte." He pauses: "Picasso is pretty funny."

Julian Barratt once said Fielding's "subconscious is very near the surface" – part of his gift as a comedian. And he is bursting with ideas. His book resembles a busy dream. It is full of manic face-painting. It features Medusa as a page three girl, ghosts locked in mortal combat and a self-portrait in the Chelsea hotel in which Fielding has a fried egg for an eye. I quiz Fielding about this habit of substituting objects for eyes – Jaffa Cakes, Polo mints, eggs … "Eyes feature heavily in my work. I have big eyes myself. Everything is in the eyes. I have a terrible sense of smell and taste. I am not interested in food at all – or smells. But I have got good hearing – like a bat."

It is not possible to meet Fielding without some animal being invoked. In his fantasy life, he is a jungle boy: "I used to have this ghost lion that came to me before gigs to give me advice," he says, and laughs. He nominates Henri Rousseau as his favourite artist and Jungle Book as his favourite book. No danger of tigers becoming extinct in Fielding's universe: they are everywhere. But it is Fielding's bold drawing of camel with a "floppy hump" that wins my vote. He explains: "The hump is foldaway. You can pack it underneath in a little papoose. But the hump is like a road map, you can never put it back the way it was."

Barratt once described Fielding's upbringing as "feral". It may not have competed with the jungle but it was wild in its urban way. He was born on 21 May 1973 and grew up in south London (nowadays, he lives in Highgate). His parents were very young – barely 19. He has described how they would party through the night and he would have to step over the bodies of their sleeping friends en route to breakfast. They weren't given to saying "no" to anything. His father, Ray, worked as a Post Office manager. His mother, Diane, worked and still does for the Home Office. He was brought up, mostly, by his French grandmother. Fielding compares her to Elvis's grandmother (pictured in the book in cool scarlet sunglasses). "When I saw a photo of Elvis's grandmother, you could tell she ruled the house. My grandma is really strong. I like strong women. That's what I respond to."

For nine years, until his brother Michael came along, Noel was an only child. That is how his career as a dreamer began. His parents were into Hawkwind, Frank Zappa, Captain Beefheart and Bryan Ferry. And for Fielding, Ferry fever has been ongoing throughout his life. Bryan Ferry featured in The Mighty Boosh, played "with blue eyebrows" by Julian Barratt. In 2010, Fielding had an exhibition at the Maison Bertaux patisserie in Greek Street, Soho, starring Ferry. The book is stuffed with Ferry portraits. And last year, he got to meet his hero, interviewing him for NME. Ferry, a former art student, was appreciative – if bemused – by Fielding's renderings of him and of captions such as, "Bryan Ferry fell on me like a giant foam wardrobe." Fielding says: "I think he got the humour of it."

Meeting Fielding today, it dawns on me that what makes his comedy so unusual it that it is benign. It is not cruel, morally ambiguous or politically dodgy. And that is because he is such a lovely character: there is no malice, not a mean bone in him. Wardrobes may topple but are made of foam. No one gets hurt. It is obvious too that he is good at making and keeping friends. He talks appreciatively, for instance, about his ex-girlfriend Dee Plume's contribution to the book. He is the sort of bloke to wear his heart on his sleeve. But what is his heart up to? He prefers to keep mum.

What about his wish to have children? About six months ago he was reported as saying he would love to have children but found it a "tricky" ambition because he knew he would not want his children brought up by a nanny. He then added that he hoped not to leave it too long. He said he would not want to become the sort of dad who would be mocked in the playground for his age. Of course his real problem would be the difficulty of getting into the playground: he would be mobbed. But I think he would make a fab father with his wild nursery humour – after all, he is already elbow deep in Plasticine.

I am not sure how much he will want to reveal about the new television show for E4, which C4 comedy commissioner Nerys Evans has described as a "passion piece". But when I ask about it, Fielding and Brown erupt at once. They talk simultaneously. Brown says: "It's like nothing you have ever seen before, it is the richest, most colourful psychedelic extravaganza: the costumes, the environments are insane." Fielding says: "It is rich, dense, like a fruitcake," – and laughs – "it's got so much in it that it would take us two weeks to make something that was going to be on screen for six seconds." It has been put together by a small team who were at art college together. They all shared a house in Hackney, east London: "Dave lived on the sofa, Nige [Nigel Coan who does the animation] with a girl from college … there were 10 of us and we were all skint.

"The show is like stream-of-consciousness sketching. I live in a Rousseau-esque jungle and there is a huge fish tank underneath my tree house. There is a manta ray inside the tank who is a music producer called Tony Reason. My brother is in it – he plays an anteater who is my butler. My cleaner is a robotic Andy Warhol." Jeff Koons comes into it too. "There is a lion that thinks that Andy Warhol is Jeff Koons. Warhol gets furious. The lion is going: 'You're Jeff Koons! I love your stuff!' " There are "tons of art references" and animation and a "soundtrack by Serge of Kasabian."

It is the animation that entrances Fielding most. He shows me the figure he created on his mobile phone of Joey Ramone "with long legs, no arms, a yellow face, red glasses and blue hair". And then he is away: he starts on Joey Ramone's story and sprints ahead, describing his wheat allergy and exploding head and a leg that turns into a golf club, which "Colin Montgomerie uses to win the open". "You are getting all this, yeah?" says Brown.

It is time for Fielding to go back to the fans and all those cameras. It is touching how much he cares for and worries about them. When I tell him some girls have been waiting since four in the morning, he winces: "They are crazy, the fans." But he talks affectionately, as if they were his co-artists. Recently, he was horrified when a 15-stone security guard started yelling at a 12-year-old. Does he mind the non-stop cameras? "I like it. I have always felt lucky I could make a living doing exactly what I wanted. I have never had to compromise." I ask Brown, who has taken countless photographs of Fielding (some of which are in the book – and in this feature) whether he thinks he has ever caught the "real" Noel Fielding? And Fielding answers: "You'll never get the real me … no, I'm joking. I am not elusive. I give myself away. I am not an actor. I have never thought of myself as an actor – though I play about 500 characters in the show. Actors play someone else. I play myself."

Our time is up. Fielding scampers off and reappears in an outfit that makes him look like a pretty bat. He squirts hairspray on, worries at his hair. There is one last question I want to ask: is there anything he takes seriously? "I don't think anything contains no comedy. Life is a comedy, isn't it? Funerals are a comedy. Death is funny. Everything is funny in the end. It is all we've got, isn't it? It is the only thing that separates us from the beasts. We laugh at stuff. Newts don't find anything funny at all. You can't get anything out of them. And rabbits – they just stare through you."